THE ROLE OF STEM CELL TRANSPLANTATION IN PATIENTS WITH R/R CLASSICAL HODGKIN LYMPHOMA TREATED WITH CHECKPOINT INHIBITORS: ITALIAN MULTICENTER EXPERIENCE

There is no agreement on the role and positioning of stem cell transplantation (SCT) in patients (pts) with relapsed/refractory (R/R) classical Hodgkin lymphoma (cHL) who undertake treatment with checkpoint inhibitors (CPI). The aim of this study is to evaluate the real-world outcomes of R/R cHL pts treated with CPI, particularly the use of consolidation with autologous (autoSCT) and allogeneic SCT (alloSCT). Observational, retrospective, multicenter study which enrolled consecutive pts with R/R cHL aged 18–70 years, treated with CPI monotherapy in Italy from January 2016 to June 2023. Primary objective was the proportion of pts who received consolidation with alloSCT. We enrolled 126 pts from 15 Italian centers. Median age at CPI start was 36 years (18–70), 54% males, 95% received first-line ABVD, 51% previously received autoSCT and 98% brentuximab vedotin. Eighty-six pts (68%) were treated with pembrolizumab, 40 (32%) with nivolumab. Overall response rate to CPI was 81%, with 49% complete responses (CRs). 107 pts (85%) were considered fit for alloSCT, of those 62 (58%) were planned to receive alloSCT. Ultimately, 41 pts (32%) received alloSCT, 36 (29%) autoSCT and 49 (39%) received no consolidation. Reasons for not performing alloSCT in candidates were progressive disease (PD) (n = 9), donor unavailability (n = 4), patient’s refusal or comorbidities (n = 4), others (n = 4). Twenty-nine out of 41 allo-transplanted pts (70%) had already received an autoSCT before CPI. Reasons for not administering a consolidation after CPI were age/comorbidity (n = 19), center’s choice (n = 9), alloSCT refusal or donor unavailability (n = 9), PD (n = 7), other (n = 5). In pts who consolidated with alloSCT or autoSCT, median PFS and OS were not reached at a median follow-up of 27 (range 7–90) and 47.5 months (range 4–99) from CPI treatment, respectively. 48-months PFS probability were 80.6% and 81% for alloSCT and autoSCT recipients. Transplant-related mortality after alloSCT was 14.6%. In non-consolidated pts, at a median follow-up of 21 months, median PFS was 27 months. Seventeen pts (35%) were still receiving CPI at last follow-up; the main reason for interruption was PD, in 18/32 pts (56%). In pts who received SCT consolidation there was no difference in terms of PFS according to the obtainment of a CR with CPI (p = 0.93 for alloSCT and p = 0.6 for autoSCT). Instead, pts who didn’t consolidate had a significantly poorer outcome if they didn’t obtain a CR with CPI (median PFS not reached versus 11 months; p < 0.001)—Figure 1. Outcomes after autoSCT and alloSCT consolidation are excellent, regardless of the response achieved with CPI; alloSCT was burdened by higher toxicity. Pts who achieved a CR with CPI showed good outcomes even without consolidation, however autoSCT should be considered if not performed before. Pts who do not achieve/loss the CR and have already performed autoSCT can be considered for alloSCT. Those who don’t achieve a CR and don’t consolidate have the worst outcome.